This invention relates to a cargo handling path setting method and apparatus for a crane, which are useful when applied to efficient cargo handling by performing a so-called simultaneous winding/traversing operation of a suspended load in which the suspended load is hoisted or lowered and traversed simultaneously.
FIG. 11 is an explanation drawing showing a conventional method for operating a crane. As illustrated in this drawing, a girder 2 is supported by legs 1 and provided horizontally. The girder 2 is provided with a trolley 3. The trolley 3 traverses along the girder 2 in the right-and-left direction in the drawing, and has a wire rope 4 for suspending a load and a wire drum (not shown) By rotationally driving the wire drum, a suspended load is hoisted and lowered.
With this crane, when a load n on a location (a) in FIG. 11 is to be carried to a location (b) over stacked loads n lying in the way, the load n is suspended at the location (a) by thewire rope 4. Then, the load n is hoisted by the wire drum, and traversed along with the trolley. Further, the load n is lowered by the wire drum, and placed on the floor at the location (b).
For the automatic operation of the crane, a so-called right-angled operation is available in which the hoisting of the suspended load n, the traversing of the trolley 3 (i.e., the traversing of the suspended load n), and the lowering of the suspended load n are performed sequentially as individual actions. This type of operation is generally employed as a simple method.
FIG. 12 shows a hoisting speed pattern, a traversing speed pattern, and a lowering speed pattern in the right-angled operation. As shown in this drawing, speed control according to trapezoidal hoisting and lowering speed patterns is performed during hoisting and lowering actions, while steadying/positioning control according to a nearly trapezoidal traversing speed pattern (steadying/positioning control pattern) is performed during a traversing action.
In the right-angled operation, the traversing action is started after completion of the hoisting action, and the lowering action is started after completion of the traversing action. As shown in FIG. 11, therefore, a cargo handling path l.sub.0 for the suspended load n takes a right-angled form. As shown in FIG. 12, the total required time T.sub.a is the sum of the time T.sub.1 required for hoisting, the time T.sub.2 required for traversing, and the time T.sub.3 required for lowering. Accordingly, cargo handling work takes plenty of time.
To make up for this drawback of the right-angled operation, a so-called simultaneous winding/traversing operation may be performed in which hoisting or lowering and traversing actions are carried out at the same time. The conventional simultaneous winding/traversing operation, however, does not go beyond an anticipatory operation merely based on past experience. The conventional simultaneous winding/traversing operation, therefore, was minimally effective for time saving, and in some cases, posed the risk of the suspended load colliding with obstacles lying around the cargo handling path.